What is the game that you spent the most time playing it on steam?

Again this? o_O

Dota 2 with 1287hrs

Counter-Strike Source

Team Fortress 2 with 1600+ hours if my memory serves me right.

Counter-Strike

Team Fortress 2 - 141 hours
Battlefield BC2 - 83 hours
Star Wars KOTOR - 40 hours

Top 3 most played games :)

Total War Shogun 2. Almost 300hours. :)

I have played over 1.600 hours of CS:S I think, and I'm still counting. So that's what I spend my time playing most on Steam. ;)

800 h TF2

tf2 - 3425 hours.

Spiral Knights. 2251 hours played in little over a year.

Team Fortress 2-
208.2 hrs on record

StarCraft2 500-1000+ hrs.

The Sims 3 with 187hrs.

Fallout new vegas around 200 hours

TF2 - 1500 hours, but Dota2 will be first, soon.

Skyrim 120hrs.

Garry's Mod 2 months exactly

(1440 hours)

TF2 with ~280 hours.

Skyrim - 313 Hours so far...

TF2. 1300+ but thats a little bit on the low side.

1.) Counter Strike 1.6 852 Hours.
2.) Counter Strike : Source 112 Hours.
3.) Left 4 Dead 2. - 47 Hours.

Counter-Strike
23.2 hrs / 3,866.4 hrs
sup

Right now the Binding of Isaac. I can't believe how addicted I've become.

Champions online with 255 hours